separating layout from content: section blocks?

["Andrew D. Crouse" <acrouse@u.washington.edu>]

To whom it may concern,

I have a large document with several distinct pieces.  Each piece has  
different layout requirements.  I can setup the layout before each  
piece, but I would prefer to separate the layout from content.   
Currently what is the best way to do this?

I have tried defining section blocks and then specifying the layout  
for the section blocks between \startsectionblockenvironment 
[mySectionBlock] and \stopsectionblockenvironment commands.  I have  
also tried the project, product, component, environment structure  
from the manuals.  I have not had success with either method.

I would be very interested to know the approach taken by more  
experienced users.

Thank you for your help.

Sincerely,

Andrew Crouse